MONTPELIER — Programmers are working “around the clock” to rewrite computer code, switch out hardware and create patches for the underperforming Vermont Health Connect website to ensure that 100,000 or so Vermonters will have insurance coverage Jan. 1.

Vermont Health Connect, the state’s version of the online health insurance marketplaces mandated by the Affordable Care Act, went live as required by the law Oct. 1. It has been plagued by performance issues, however.

Gov. Peter Shumlin, at his weekly news conference Thursday, continued to vow that the problems will be corrected in time for people required to obtain insurance on the exchange. He repeatedly declined to discuss contingency plans.

Mark Larson, commissioner of Vermont Health Access, said in an interview Friday that the state exchange has struggled with four main issues: speed, verification of identities, communication with a federal hub, and errors when applications are submitted electronically.

Fixes performed by the state’s contractor, CGI Systems and Technologies, have included addressing the site’s security processes.

Verifying identity proved to be problematic with the site’s original makeup. Larson said the state has “taken significant steps” to secure private information but that those measures contributed to the problems with functionality.

“That means there are pretty rigid security barriers that you have to get through to sign in,” he said. “What we were finding is that people were getting stuck too frequently. If you think about an airport, they were getting stuck in security.”

CGI staffers were able to remove some of the barriers, according to Larson, who declined to offer more specifics for fear of compromising the site’s security. Personal information has not been compromised, he said.

CGI is now trying to ensure that various sections of the online portal are able to interact with each other correctly. The system requires the state site to submit data to a federal hub to verify identity, income and citizenship, among other factors. The federal hub is supposed to accept the data and return its own information.

About 30 percent of the attempted exchanges with the federal hub were unsuccessful after the site went live. Changes made to the site have nearly eliminated those failures, Larson said.

“Our health system is just really complicated, and trying to create a portal to make convenient and real-time decisions about coverage means connecting lots of pieces to a really complicated system,” he said.

The site’s speed has improved by more than 300 percent since the Oct. 1 launch, he said. That was achieved by altering code and hardware.

The site’s initial slowness also contributed to communication problems between Vermont Health Connect and the federal hub.

Many attempts would “time out” before the data exchange was completed. And at times frustrated users would click the “next” button several times while they waited for results, exacerbating the wait time.

“You’re waiting in a long line of people, and every time you press ‘next’ you’re inviting a friend to join you in line,” Larson said. “That’s where we actually made some changes so at those points we made it so you can’t press ‘next’ again until it’s done.”

Addressing the various error messages has required the most work. Larson said some of the errors have been fixed by simply adjusting settings. Others required changes to the original computer code.

Still, the fixes must be meticulously tested to ensure they will not affect the site in unexpected ways. That has prevented programmers from implementing fixes more quickly, according to Larson.

The exchange site also launched without a major component: the ability to accept payment. Shumlin had promised that function would be ready by Nov. 1 but has since retreated. He said it should now be ready in early November.

Initial testing of the payment system that ties into the insurance companies offering plans has taken place, according to Larson. That testing will continue until it is working properly, he said.

“Between now and through next week, testing is really the big focus of our activity,” Larson said. “... We have tested sending files, and we’ve learned things that need to be adjusted. We’ve made those adjustments, and the results continue to improve with each step that we take.”

Vermont is one of 14 states that opted to create their own exchanges rather than using the federal one, which has seen its own significant problems.

CGI is also the major contractor for the federal site. Larson said the company is not stretched too thin, though, and that Vermont continues to receive the resources it needs.

“They are really two complete divisions or entities of CGI that are working on our exchange and the federal exchange,” he said. “So, we have our own dedicated team and we’re not competing for resources or use of those resources here in Vermont with the federal exchange.”

In fact, CGI has increased the number of people working on Vermont Health Connect since Oct. 1, he said.

The rocky rollout has provided fodder for Republicans who have long questioned the viability of the exchanges. The Vermont House and Senate minority leaders, Rep. Don Turner, R-Milton, and Sen. Joe Benning, R-Caledonia, called this week for Shumlin to exercise a provision in state law that would allow current health insurance plans to be extended into next year.

If the online exchange is not fully functional by Dec. 1, they will call for putting “the interests of Vermonters first by deploying the safety provision in the current law or calling for a special session of the Legislature to develop an alternative plan,” they wrote in a joint statement.

Republican Lt. Gov. Phil Scott on Friday called that position reasonable.

“I think there should be benchmarks and that way we can take some of the politics out of it,” he said on Vermont Public Radio’s “Vermont Edition.” “If we don’t meet a certain goal by a certain date then we should back up and make sure that we protect Vermonters. I just want to be realistic, pragmatic. I don’t want to paint anyone into a corner. It doesn’t mean that anybody has to admit defeat.”

State employees and CGI staff are frustrated with the scope of problems that have emerged with the site, Larson said, but they remain motivated to address the issues and make it work.

They “aren’t losing sight of the fact that being successful is a really important step forward in creating greater access to affordable and comprehensive health care,” he said.